1. Field of the Invention
This invention relates to a video signal recording apparatus and more particularly to an apparatus for recording a digital audio signal on a tape-shaped recording medium along with an analog video signal.
2. Description of the Related Art
The conventional apparatuses of the above stated kind are described in detail below with a helical scanning type magnetic recording and/or reproducing apparatus (hereinafter referred to as VTR) taken as an example.
Among the conventional VTRs, there have been proposed and made practical VTRs which are arranged to permit the so-called concatenated recording from a desired recording position with an adequate boundary between one scene and another in such a manner that the end of a preceding scene is detected by bringing a recording action to a pause and then by rewinding a tape-shaped recording medium before resuming the recording action. The start position of a concatenated recording operation has been arranged to be found by one of varied methods, including among others: (i) A method of determining recording start timing simply by a tape rewinding speed and the traveling speed of the tape obtained immediately before the start of recording. (ii) A method of determining it by a number of control signals which were recorded along the edge part of the tape in the longitudinal direction of the tape and have been reproduced before rewinding and by a number of the control signals reproduced before a start of recording. (iii) A method of determining it by the numbers of pulses generated by a frequency generator disposed at a capstan motor and is counted when the tape is rewound and counted immediately before a start of recording. (iv) A method of determining it by varying the recording pattern of tracking control pilot signals and by detecting these varied patterns.
In accordance with the method (i) above, in order to prevent any part of each scene from dropping out at a recording end position or at a recording resuming position, it is necessary to provide some allowance for an error in setting the timing. As a result, an overlapped recording amount increases and, in some case, the boundary between one scene and another might appear in an undesired part. In the method (ii), it necessitates use of some area along the edge part of the tape and is not applicable to any apparatus other than a VTR of the kind using an additional head solely for the purpose of recording the control signals. In the case of the method (iii), some slippage of the tape that tends to occur between a capstan roller and a pinch roller at a starting time results in an error in the recording start position. In the case of the method (iv), no tracking control signal is obtainable from a part where a change occurs in the recording pattern. Therefore, while this shortcoming is ignorable for a servo device of a slow responsivity, the servo device would momentarily go astray. Every one of these methods thus has presented a problem.
Further, for attaining the above stated purpose, it is also conceivable to multiplex some suitable mark signal with the analog video signal. However, the analog video signal then would be affected by that arrangement.